Power-operated nailing devices are well known in which the nails are associated together in a strip, and are fed from a magazine. One particularly advantageous form of such a nailing device employs a drum-shaped magazine in which the nails are stored in a generally spiral coil. This type of nailing device and magazine can accommodate a larger number of nails in the magazine, than is the case with nailing devices in which the nails must be inserted in a magazine which is essentially linear. In the linear type of magazine, the strip of nails must also be linear. There are severe practical limitations on the length of such a linear strip that can be employed without inconveniencing the operator of the device.
In the case of a spiral coil of nails, however, a generally cylindrical or drum-shaped form of magazine is employed, and consequently a much greater number of nails can be employed in the strip, without inconveniencing the operator.
It is known to secure the nails together in such a nailing strip by a variety of different media. In linear nailing strips it is known to employ lengths of wire, welded to the individual nails, and also to employ a plastic adhesive medium, and also in some cases nails are simply held together by paper tapes. All of these systems have various advantages and various drawbacks. In the case of coiled nails however in the past, the only practical and satisfactory form of medium has been two lengths of wire welded to the nails at spaced-apart intervals. The nails are welded on to the two wires, while moving along a linear path. The lengths of wire are cut at suitable intervals, and the nails are then coiled into coiled strips of the appropriate size. This system functions satisfactorily, insofar as it lends itself to efficient high speed production techniques, and effectively secures the nails in the strip, until they are delivered to the nailing device for insertion into a wooden work piece.
It is, however, known that the use of such wires may cause problems. In the operation of the nailing device, pieces of wire may become detached from a nail and may lodge in the device, causing it to malfunction.
In spite of these problems however, in the past, alternative media such as plastic materials, paper and the like have been considered as unsatisfactory for forming nails into a coiled nailing strip. One of the problems associated with the use of media other than wire, for joining nails, is the design of the feed mechanisms used in nailing devices for feeding nailing strips. The feed mechanisms employ feed pawls of a design which is adapted to drag the strip from the magazine, and feed the nails one by one into a barrel portion of the nailing device where they are then struck by a plunger. The shaping and design of the feed pawls employed in such nailing devices are such that it is necessary for them to make a positive engagement with the shank of each nail, from one side of the strip, while the other side of the strip is securely held against a wall in the feed mechanism. In the type of coil formed with wires, welded to the nail shanks, the welds provide a solid effective bond between the nails and the wires, on one side of the nail shank, while leaving the opposite sides of the nail shanks clear, and therefore free for engagement by the feed pawls.
In the past, attempts have been made to provide linear nailing strips in which the bonding media comprised extruded ribbons of plastic. Four such ribbons were extruded: two on one side of the nails; and two on the other side to provide two spaced apart parallel bonding strips of plastic material. In this system, the extruded ribbons of plastic, immediately after extrusion, were subjected to the action of forming dies, to compress the ribbons of plastic together between the nails, so that they formed an integral strip or web of material extending between adjacent nails. This system, however, has not proved to be suitable for use in all types of nailing devices employing coiled nail strips. The plastics material bonding the nails together interferes with the operation of the feed pawls, in some cases unless they are specially designed to accept them. The collars defined curving surfaces which prevented a secure contact being made by the feed pawls.